Wheels from Opel Meriva on Saab 900: compatible?

No, the centre bore is too small

Same 5x110 PCD, but the centre bore of the wheels from Opel Meriva (65.1 mm) is smaller than the hub of Saab 900 (71.5 mm): they will not fit without being re-bored by a professional.

Opel Merivafrom 2010Saab 9001978–1988
PCD5x1104x114.3 / 4x108 / 5x110
Centre bore65.1 mm71.5 mm
ThreadM12x1.50Ecrous - 1/2 - 20 UN
Original wheels 6.5Jx15 ET35 R
R
≈6Jx15 ET49

≈: width estimated from the original tyre size.

Before fitting the wheels

An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of Saab 900 (Ecrous - 1/2 - 20 UN), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.

And the other way round: wheels from Saab 900 on Opel Meriva?